Client-server communication software can improve over time, or be replaced by better software. Picking a style based on technical limitations that will be superseded anyway is surely what you're arguing against?

As a more general point, using spaces instead of tabs can still be handled easily by IDEs. It's possible to recognise that something is supposed to be an "indent", and then space it according to what your preferences are. Whether any current IDEs do that, I don't know.